We had previously cloned partial cDNAs for G proteins by a PCR amplification strategy. This year we have focused on the cloning and characterization of G protein genes in the cochlea. We made a cDNA library from the cochlea of CBA/J mice and screened it using a PCR amplified cDNA. A clone encoding Gi2alpha was further analyzed. In the coding region, this clone has a 99.2% identity in DNA sequence with that of the macrophage clone, while the 3' non-coding region of this clone had a 87.3% identity. The antibody raised against the Gi2alpha was used for the immunolocalization of this protein in the mice cochlea. It was found that the Gi2alpha is localized in outer and inner hair cells. Further immunocytochemical study using antibodies raised against other species of G proteins suggests that there could be a unique distribution pattern of G proteins among the component cells of the cochlea.